Long Term Evolution (LTE) is a radio technology designed to increase the capacity and speed of mobile telephone networks and provide for an end-to-end Internet Protocol (IP) service delivery of media to help support the demands for multimedia services that are already experienced in wired networks. Currently, LTE comprises a set of enhancements to the Universal Mobile Telecommunications System (UMTS), which is described in a suite of Technical Specifications (TS) developed within and publicized by Third (3rd) Generation Partnership Project (3GPP). Copies of the 3GPP TSs can be obtained online at http://www.3gpp.org/specifications, or by writing to 3GPP Mobile Competence Centre (c/o ETSI), 650, route des Lucioles, 06921 Sophia-Antipolis Cedex, FRANCE.
LTE, in part, provides for a flat Internet Protocol (IP)-based network architecture designed to ensure support for, and mobility between, some legacy or non-3GPP systems such as, for instance, GPRS (general packet radio service) and WiMAX (Worldwide Interoperability for Microwave Access). Some of the main advantages of LTE are high throughput, low latency, plug and play, FDD (frequency-division duplex) and TDD (time-division duplex) in the same platform, improved end user experience, simple architecture resulting in low operating costs, and interoperability with older standard wireless technologies such as GSM (Global Systems for Mobile Communications), cdmaOne, W-CDMA (UMTS), and CDMA2000. Many major carriers have started to support LTE in their networks.
LTE and other 3GPP compliant systems (meaning systems having elements that operate in compliance with 3GPP TSs) also provide Multimedia Broadcast/Multicast Service (MBMS) point-to-multipoint (PTM) transport of media to User Equipment (UEs) operating on the system.
To support MBMS, LTE offers functionality to transmit MBMS over a Single Frequency Network (MBSFN), where a time-synchronized common waveform is transmitted from multiple cells for a given duration.
The locations of UEs within MBSFN areas can vary. To help ensure that all UEs can properly decode radio frequency (RF) signals received from enhanced Node Bs (eNodeBs) (and thus help achieve good RF reception by all UEs that should receive the service), the eNodeBs can be configured to transmit at a low modulation and coding scheme (MCS) level, where the semantics and for the MCS level are defined in 3GPP TS 36.213 “Evolved Universal Terrestrial Radio Access (E-UTRA); Physical layer procedures.” To be able to properly decode received RF signals, a UE in a harder RF environment will need to receive RF signals that were modulated and coded at a lower MCS level than a UE in a better RF environment. Unfortunately, always using a low MCS level may unnecessarily consume an undue amount of RF resources. For example, in some cases it may be possible to transmit at a higher MCS level and still achieve adequate reception by all UEs within MBSFN areas that are to receive MBMS.
Accordingly, there is a need for improvements to the MBMS mechanisms that are currently used in conjunction with 3GPP compliant systems. It would be desirable to provide methods, systems and apparatus that can help reduce resource utilization, while at the same time ensuring that all the UEs are able to receive properly decode the received RF signals. It would be desirable if such methods, systems and apparatus were easy to implement using communication systems such as those that implement existing LTE infrastructure in a way that does not impact the UE or existing standards.
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The apparatus and method components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.